Detector Row Research Articles

孤立性特発性腹腔動脈解離に続発した解離性脾動脈瘤破裂の2例(Ruptured dissected splenic artery aneurysms secondary to isolated spontaneous celiac artery dissection: a report of two cases)

【症例1】52歳の男性。腹痛を主訴に近医を受診したところ，腹部造影CTで急性膵炎および脾動脈瘤破裂と診断され当院紹介となった。当院CTでは腹腔動脈起始部の解離と仮性動脈瘤を認めた。血管内治療を試みたが，脾動脈遠位の屈曲・蛇行が強く，金属コイルとNBCA併用による近位塞栓で終了とした。不完全塞栓であったため最終的には手術治療を要した。【症例2】53歳の男性。受傷2日前に突然の腹痛を自覚。受傷当日，乗用車運転中に意識消失し対向車と正面衝突し搬送となった。来院時ショック状態であり，腹部超音波検査では腹腔内液体貯留を認め，造影CTでは腹腔動脈起始部より脾動脈遠位に至る偽腔開存型解離および解離性脾動脈瘤破裂と周囲血腫を認めた。腹腔動脈起始部は正中弓状靱帯圧迫症候群により狭小化していた。血管内治療を施行したところ，脾動脈解離の真腔は偽腔に圧排され完全閉塞し，偽腔より横隔脾間膜内への造影剤漏出を認めた。偽腔の近位・遠位を金属コイルで塞栓し止血を得た。経過観察後のCTでは脾門部に仮性動脈瘤の出現を認め，金属コイル・NBCA塞栓術を追加し根治し得た。孤立性特発性腹腔動脈解離に伴う解離性脾動脈瘤破裂は非常に稀ではあるが，内因性腹部出血の鑑別の一つとして考慮すべきであり，発症様式や全身状態により各施設で最適な止血方法を選択する必要がある。 Here we report the features of two cases of ruptured dissected splenic artery aneurysm associated with isolated spontaneous celiac artery dissection encountered in our institute. Case 1: A 52–year–old male was referred to us following diagnosis with acute pancreatitis with pancreatic pseudocyst, dissection of the origin of the celiac artery, and a dissecting pseudoaneurysm of the splenic artery on computed tomography(CT). Endovascular treatment was attempted, but the distal splenic artery was difficult to reach due to high flexion and tortuosity; therefore, proximal embolization alone was performed. Follow–up CT showed incomplete embolization, and radical surgical treatment was subsequently performed. Case 2: A 53–year–old male lost consciousness while driving a passenger car and was injured in a head–on collision with an oncoming car. CT showed dissection from the origin of the celiac artery to the proximal splenic artery and rupture of the splenic artery aneurysm. The celiac artery was narrowed due to median arcuate ligament syndrome. Endovascular treatment was performed, the proximal and distal portions of the false lumen were embolized with coil and cyanoacrylate, and hemostasis was achieved. Follow–up CT revealed a pseudoaneurysm at the splenic hilum, and embolization was performed again. Although, very rare cases, we should consider as one of the differentials diagnoses. 孤立性特発性腹部内臓動脈解離は稀な病態であるが，腹腔動脈解離は上腸間膜動脈解離に次いで多いとされている 1。孤立性特発性腹腔動脈解離（isolated spontaneous celiac artery dissection: ISCAD）はmulti detector–row CT（MDCT）の普及により報告数が近年増加しているものの，無症候から症候性に至るまで臨床経過は様々である。一般的には初回治療として保存的治療を選択することが多いが，合併症を有する例では侵襲的治療が選択される 2。今回我々は，解離性脾動脈瘤破裂を伴ったISCADの2例を経験したため，文献的考察とともに報告する。 本稿は倫理委員会の承認を要しない症例報告である。また，個人情報保護法に基づき匿名化されており，患者家族から論文の出版に関する同意を得ている。 患 者：52歳の男性 主 訴：左側腹部痛 既往歴：特記事項なし 飲酒歴：焼酎500〜1,000mL/日 喫煙歴：20〜30本/日×30年間 現病歴：来院10日前より左側腹部痛を自覚していたが，徐々に増悪したために前医へ救急搬送された。造影CT検査で急性膵炎および脾動脈瘤破裂と診断され，当院へ転送となった。 来院時現症：意識レベルJapan coma scale（JCS）I–0，Glasgow coma scale（GCS）E4V5M6，呼吸数18/分，心拍数110/分，血圧140/80mmHg，体温37.2℃（腋窩），SpO2 100%（室内気）腹部は平坦・軟であり左側腹部の自発痛はほぼ消失していた。血液検査では白血球17,000/μL，CRP 6.92mg/dLと軽度の炎症所見を認めた。Amyは70U/Lと基準値内であった。 腹部造影CT動脈相では，腹腔動脈起始部は解離しておりISCADの所見を認めた（補足図1a）。動脈解離は腹腔動脈から脾動脈中程まで連続しており，脾動脈起始部は偽腔に圧排され高度に狭小化しており，偽腔は瘤状に拡張していた。さらに，破裂した偽腔周囲には最大径約25mmの不整に拡張した仮性動脈瘤を認めた（補足図1b）。また，膵体尾部の腫大と膵周囲の脂肪織濃度上昇を認め，急性膵炎の所見を認めた（補足図1c）。 初療経過：循環動態は安定していたため，仮性動脈瘤に対し動脈塞栓術（transcatheter aterial embolization: TAE）の方針とした。腹腔動脈造影では，腹腔動脈起始部から脾動脈へ及ぶ解離を認め，解離性脾動脈瘤を形成していた。解離性脾動脈瘤の周囲には最大径47mmの血腫を認め，仮性動脈瘤を形成していた（補足図2a）。脾動脈の真腔は拡張した偽腔に圧排されて狭小化しておりアプローチ不能であったため，偽腔よりアプローチした。偽腔から解離性脾動脈瘤遠位の選択を試みたが，屈曲と蛇行が強く困難であった。そのため，アイソレーションを断念し，仮性動脈瘤に連続する解離性脾動脈瘤内をコイル6本でパッキングし，解離性脾動脈瘤近位に2本のコイルを留置して50%NBCA 2mLを注入した。NBCAは解離性脾動脈瘤の尾側に停滞した。その後の造影では，解離性脾動脈瘤の一部に造影効果を認めたが，これ以上の塞栓は技術的に困難と判断し手技を終了した（補足図2b）。 入院後経過：TAE後は腹痛の再燃や貧血の進行なく経過したが，第4病日の造影CTではコイル塞栓部腹側に結節状の造影効果が残存し，塞栓部の遠位にも血流を認めた（補足図2c）。不完全塞栓であったがTAEによる再アプローチは困難と考え，待機的に第8病日に手術となった。開腹時，活動性出血はほぼ認めなかった。膵体尾部に膵炎の影響と思われる高度癒着を認め，瘤との剥離は困難であった。脾動静脈を根部で結紮し，膵体尾部・脾臓合併切除を行った（補足図3a, b）。術中出血量2,320mL，濃厚赤血球輸血計4単位使用した。術後経過は良好で第25病日に退院となった。切除膵の病理組織診断では，膵炎の炎症が脾動脈へ波及し，脾動脈外膜が破壊されている所見を認めた。 患 者：53歳の男性 主 訴：意識消失，腹痛 既往歴：糖尿病，高血圧 現病歴：受傷2日前の早朝に突然の激しい腹痛とめまいを自覚したが，自宅で様子を見ていた。受傷当日，乗用車を運転中に意識消失感が出現し，車を停車させたところで対向車と正面衝突し救急要請となった。救急隊接触時ショック状態であり，ドクターヘリで当院搬送となった。 来院時現症：意識レベルJCS I–1，GCS E4V5M6，呼吸数18/分，心拍数121/分，血圧81/54mmHg，体温35.2℃（腋窩温），SpO2 99%（酸素10Lリザーバーマスク），瞳孔径は両側3.0mmで対光反射は迅速であった。腹部超音波検査でモリソン窩，脾周囲，膀胱直腸窩に液体貯留を認めた。体表上は明確な外傷痕は認めず，腹部も平坦軟であったが，上腹部に軽度の圧痛を認めた。血液・生化学検査では，白血球の上昇（25,100/μL）と貧血（Hb 10.2mg/dL）を認めたほか，Cr 1.08mg/dL，CRP 2.29mg/dL，乳酸32mg/dLと上昇を認めた。Amyは110U/Lと基準値内であった。 初療経過：ドクターヘリ医師接触時は血圧測定不能であったが，現場より初期輸液，O型赤血球輸血開始後，来院時収縮期血圧は80mmHg以上に上昇したため，直ちに腹部造影CTを施行した。腹部造影CTでは血性腹水貯留を認め，腹腔動脈起始部は正中弓状靱帯圧迫症候群（median arcuate ligament syndrome: MALS）により狭小化（補足図4a）しており，かつ解離（ISCAD）を認めた（補足図4b）。ISCADは脾動脈遠位に及び，解離性脾動脈瘤の破裂に伴う仮性動脈瘤が形成されていた。さらに，横隔脾間膜内には大量の血腫を伴っていた（補足図4c）。来院時は、“外傷性”腹腔内出血として初療を進めていたが，受傷機転が軽微なこと，腹部に外傷痕を認めないこと，来院2日前からの腹痛と意識消失のエピソードがあることを考慮し，解離性脾動脈瘤破裂による出血性ショックと最終的に判断した。開腹止血術も考慮したが，輸液・輸血により循環動態の安定化が得られたこと，CT上腸管損傷などの絶対的に手術介入を要する病態がないことからTAEの方針とした。腹腔動脈造影では仮性動脈瘤はやや遅れて描出された（補足図5a）。膵尾枝や大膵動脈は描出されず，遠位で僅かに脾実質が造影された。腹腔動脈造影を施行したところ，腹腔動脈解離に続く解離性脾動脈瘤の真腔は偽腔に圧排されて狭小化し，完全閉塞していた。そのため，偽腔内へガイドワイヤーを進め，偽腔内から仮性動脈瘤の遠位をコイル計5本，近位をコイル計7本にてアイソレーションした（補足図5b）。最終的に腹腔動脈造影，上腸間膜動脈造影で仮性動脈瘤が描出されないことと，短胃動脈から脾実質の造影効果が保たれていることを確認して手技を終了した。 入院後経過：循環動態は安定して経過し，貧血進行もなく，止血は得られたと判断した。第8病日の造影CTでは，脾門部に短胃動脈を血液流入路とする仮性動脈瘤の出現を認めた。瘤径は小さく血栓化を期待し経過観察を行ったが，第18病日のCTで瘤径14×16mmと増大を認めたため再度TAEを施行した。腹腔動脈から胃十二指腸動脈，胃大網動脈を介してアプローチし，仮性動脈瘤近位と遠位で金属コイル2本と40%NBCAにて塞栓を行った（補足図6a, b）。脾臓血流は，短胃動脈・後胃動脈を介して温存された。その後は経過良好で，第21病日に退院となった。 今回我々は，ISCADを伴う解離性脾動脈瘤破裂の症例で，それぞれ異なる治療アプローチを要した2症例を経験した。ISCADはMDCTの普及により近年報告数が増加しており，初回治療として降圧，鎮痛，抗血小板療法，抗凝固療法などによる保存的治療を選択されることが多い。腹腔内出血などの合併症を有する例では侵襲的治療が選択されるが，確立した治療法はなく，症例により手術あるいは血管内治療が選択されている 2, 3, 4。 侵襲的治療の適応として，症状持続，腹腔動脈径拡大（≧15～20mm）や瘤化，真腔の狭小化や閉塞による臓器虚血，動脈瘤破裂が挙げられる 5。ISCAD 169例のシステマティックレビューでは血管内治療が11.8%に，開腹手術が8.9%に行われており，近年では血管内治療が主流となっている 6。また，別のシステマティックレビュー（68症例）では，解離の進展範囲に関し腹腔動脈限局が22.6%，脾動脈への進展が50.9%，総肝動脈への進展が45.3%と報告されている 5。破裂症例は腹腔動脈1.2%，脾動脈2.9%に認め全例死亡している 5, 6。このように，ISCADから破裂に至る症例は非常に稀であり，文献検索した範囲では腹腔動脈起始部の解離が遠位へ進展し破裂した例は4例のみであった 2, 3, 7, 8。 今回提示した2症例では，ISCADが脾動脈遠位まで解離を来し，かつ解離性動脈瘤破裂に至った点と，その背景にそれぞれ膵炎やMALSを有していた点で非常に稀な症例であった。これまでにISCADの成因として，動脈硬化，血管炎，線維筋性異形成，結合織疾患（Marfan，Ehlers–Danlos症候群），結節性多発動脈炎，segmental arterial mediolysis，梅毒や真菌感染症などが報告されている 2。 症例1では，循環動態が安定していたことからTAEを第一選択としたが，脾動脈の屈曲・蛇行と狭小化が著しく，不完全塞栓となり最終的に手術を要した。ISCADの解離が脾動脈へ進展した結果解離性脾動脈瘤を形成し，さらに脆弱性の高い偽腔に急性膵炎の炎症が波及し破裂を来し，仮性動脈瘤を形成したものと考えられた。ISCADそのものの成因として膵炎が背景となっていたかに関しては報告が存在しない。症例2は，MALSに続発したISCADが脾動脈に進展し，解離性脾動脈瘤の形成から破裂に至った症例であった。MALSがISCADの発生に関与した症例は過去に報告されており，MALSに腹腔動脈解離が合併し膵十二指腸動脈瘤破裂に至った例 9や，MALSに腹腔動脈解離を伴い血管内治療を施行した例 10，および血管内治療に加え腹腔鏡による弓状靭帯切離を施行した例 11の3症例のみが存在している。MALSからISCADを生ずる機序は，腹腔動脈起始部の物理的狭小化によって血管内腔の圧上昇を来し，内膜と中膜の解離を生じるためと考えられる。無症候性のMALSが多く存在することは知られており，剖検例の検討では約1/3にMALSによる腹腔動脈圧迫を認めたとの報告もある 12, 13。また，CTなどの画像検査で約7%に腹腔動脈の無症候性狭窄が発見されたとの報告もある 14。ゆえに，症例2のように無症候性のMALSにISCADを潜在的に有している例も少なからず存在する可能性がある。なお，CTでISCADが偶発的に見つかった場合でも，循環動態が安定しており破裂や仮性動脈瘤を伴っていない場合にはルーチンでの血管造影は不要であり，MDCTでの形態的評価と経時的な経過観察で十分と考える。症例2ではTAEを第一選択としたが，もし仮に初期輸液にて循環動態の安定化が得られなかった場合，CT撮像ができないまま外傷性腹腔内出血として開腹止血術を先行させていた可能性があり，その場合ISCADによる内因性の解離性脾動脈瘤破裂との診断がつかなかった可能性がある。このように内臓動脈瘤破裂は，発症様式や全身状態においても選択される治療法が異なる病態であり，施設のリソースや各科のバックアップ体制なども考慮し，個々の施設で最適な止血方法を選択する必要があると考える。血管内治療，外科的治療のいずれを選択するにしても，初療を担う救急医がリーダーとして治療方針を決定し，専門的治療につなげることが要求されるため，内因性腹部出血の鑑別の一つとして常にこのような病態を念頭に置く必要がある。 また，MALSにおいては，根本原因である弓状靭帯圧迫を解除しないと，腹腔動脈，脾動脈塞栓に伴い，理論的に側副路への負担が増し将来的に瘤化から破裂を来す危険が残存する。現在ではより低侵襲な腹腔鏡下切離術が可能であり，ステントグラフト治療と組み合わせた根治的治療が将来的に期待されよう。 ISCADによる解離性脾動脈瘤破裂の2例を経験した。内因性腹部出血の鑑別としてISCADの破裂を念頭に入れる必要がある。 本稿における利益相反はない。 Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Assessment of Utility of Computed Tomography Pulmonary Angiography in Pulmonary Embolism

Background: Among all the available diagnostic tools, computed tomography (CT) is the preferred diagnostic tool for clinically suspected pulmonary embolism (PE) cases. Further, with the development of multi–detector row CT (MDCT) technology, previous limitations of CT have been overcome effectively. For patients with clinical suspicion of PE, MDCT pulmonary angiography has become the first line of modality for the diagnosis. Aims and Objectives: To evaluate various common observations of CT pulmonary angiography (CTPA) in suspected cases of PE that could accurately determine the choice of management. Materials and Methods: Fifty patients with clinically suspected PE referred to the department of Radiodiagnosis for CTPA from various departments were studied in the cross-sectional study. CT images were obtained with a SIEMENS 64-slice multi-detector CT scanner (somatom definition AS). Images were reconstructed into 3D, axial, coronal, sagittal maximum intensity projection sections, and volume rendering techniques. The axial as well as reformatted coronal and sagittal images were evaluated. Results: The incidence of PE was 52%. The incidence of PE was highest in patients older than 60 years (30.8%) and males (30.3%; p=0.662). The most common symptoms evoking a suspicion of pulmonary embolism were dyspnea (69.2%), followed by chest pain (15.4%), cough (11.5%), and hemoptysis (3.8%). Out of 26 patients who had PE, 61.5% had right ventricular enlargement. DVT (23.1%) was the most common past history. The majority of the patients had thrombus in the right main pulmonary artery (21.1 %), followed by the left main pulmonary artery (19.3 %). Conclusion: In clinically suspected cases of PE, MDCT pulmonary angiography was a useful diagnostic tool. CTPA is the modality of choice for its rapid, minimally invasive, and well-tolerated nature.

Fast and Enhanced MMW Imaging System Using a Simple Row Detector Circuit with GDDs as Sensor Elements and an FFT-Based Signal Acquisition System.

The relatively high atmospheric propagation of millimeter-waves (MMW) was found to be one of the most critical reasons for the development of reliable sensors for MMW detection. According to previous research works, it has been already shown that incident MMW radiation on a glow discharge detector (GDD) can increase the discharge current. Hence, the electrical mode of detection can be employed to detect the presence of MMW radiation. In this article, a new design of a row detector using GDDs as pixel elements, and the influence of MMW incidence on GDD's discharge current, were acquired using an elementary data acquisition (DAQ) platform. The DAQ system computes the averaged Fast Fourier Transform (FFT) spectrum of the time signal and returns the FFT results as magnitude based on the level of detection. An FFT-based signal acquisition proved to be a better alternative to the lock-in detection that was commonly used in MMW detection systems. This improved detection circuit provides enhanced noise filtering, thereby resulting in better MMW images within a short time. The overhead expense of the entire system is very low, as it can avoid lock-in amplifier stages that were previously used for signal enhancement. A scanning mechanism using a motorized translation stage (step motor) is involved to place and align the row detector in the image plane. The scanning can be carried out vertically to perform the imaging, by configuring the step motor after selecting the desired step size and position. A simplified version of the MMW detection circuit with a dedicated over-voltage protection facility is presented here. This made the detection system more stable and reliable during its operation. The MMW detection circuit demonstrated in this work was found to be a milestone to develop larger focal plane arrays (FPA) with very inexpensive sensor elements.

COMPARISON OF THE 64- AND 80-DETECTOR ROW COMPUTED TOMOGRAPHY AMONG THE CT NUMBER AND RADIATION DOSE DURING LOWER EXTREMITY COMPUTED TOMOGRAPHY ANGIOGRAPHY.

To compare the computed tomography (CT) number and the radiation dose between the 64 (group A) and 80-detector row (group B) during lower extremity computed tomography angiography (LE-CTA). We enrolled 144 patients underwent LE-CTA and compared the CT number for the popliteal arteries, radiation dose and the rate of the optimal CT number during the LE-CTA exceeding 200 HU between the two groups. The CT number for the popliteal arteries and mean dose-length product was significantly higher in Group A than in Group B (P<0.01). The rate of the optimal CT number for the popliteal arteries was 23.6% with Group B scanner and 56.9% with Group A (P<0.05). The 64-detector row CT was significantly higher in the CT number for the popliteal arteries, radiation dose and rate of the optimal CT number during the LE-CTA than the 80-detector row. Depiction ability did not improve by using a high CT scanner with a wider detector during LE-CTA.

Pitch Angle Isotropy of Relativistic Electron Microbursts as Observed by SAMPEX/HILT: Statistical and Storm‐Time Properties

AbstractObservations of relativistic electron precipitation events from Earth's inner magnetosphere to the upper atmosphere provide essential information about the source/loss processes and dynamics of Earth's radiation belts. Equatorial electron pitch angle isotropy can be an indicator of electron precipitation into the atmosphere, with isotropic populations resulting in a full bounce loss cone (BLC) and anisotropic populations resulting in an emptier BLC. Here we study electron microbursts, which are ˜100 millisecond duration streams of relativistic electrons thought to be scattered into the BLC by particle‐wave scattering. By measuring the ratios of &gt;1 MeV electron flux across different detector rows in the Heavy Ion Large Telescope (HILT) instrument onboard the Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX) satellite, we quantify the pitch angle isotropy of an electron population. Applying this calculation to microburst events, we have determined the dependence of microburst pitch angle distributions on burst magnitude, magnetic local time (MLT), L‐Shell, and storm phase. We found that high flux magnitude microbursts are typically highly isotropic, while lower flux magnitude microbursts have varying degrees of anisotropy. Furthermore, microbursts are most isotropic as compared to the background population in the afternoon/evening sector as well as initial and main phases of geomagnetic storms. These results have important implications for microburst scattering mechanisms as well as quantification of precipitation driven by this process.

Anemia Detection with Contrast-enhanced Photon-counting CT

HomeRadiologyVol. 305, No. 2 PreviousNext CommunicationsFree AccessErratumAnemia Detection with Contrast-enhanced Photon-counting CTJonathan D. Dodd, Roisin MacDermottJonathan D. Dodd, Roisin MacDermottJonathan D. DoddRoisin MacDermottPublished Online:Oct 24 2022https://doi.org/10.1148/radiol.229023MoreSectionsPDF ToolsImage ViewerAdd to favoritesCiteTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinked In Originally published in:https://doi.org/10.1148/radiol.221471Erratum in:https://doi.org/10.1148/radiol.229023The quote on the first page was changed to read …became clearly visible on noncontrast CT images in canine hearts. The dose-length product unit was changed to mGy ∙ cm, and the associated value was changed from 59 to 592. Reference 4 DOI was changed to https://doi.org/10.1148/radiol.220063.Article HistoryPublished online: Oct 24 2022Published in print: Nov 2022 FiguresReferencesRelatedDetailsAccompanying This ArticleAnemia Detection with Contrast-enhanced Photon-counting CTJul 26 2022RadiologyRecommended Articles Influence of Heart Rate on Image Quality and Radiation Dose Exposure in Coronary CT AngiographyRadiology2021Volume: 300Issue: 3pp. 701-703Slow and Steady Wins the Race: Lower Heart Rates Improve Diagnostic Quality for Coronary CT AngiographyRadiology2021Volume: 300Issue: 3pp. 704-705Radiation Dose Reduction by Using CT with Iterative Model Reconstruction in Patients with Pulmonary Invasive Fungal InfectionRadiology2018Volume: 288Issue: 1pp. 285-292Evaluation of Kidney Stones with Reduced–Radiation Dose CT: Progress from 2011−2012 to 2015−2016—Not There YetRadiology2017Volume: 286Issue: 2pp. 581-589MRI of Iron Oxide Nanoparticles and Myeloperoxidase Activity Links Inflammation to Brain Edema in Experimental Cerebral MalariaRadiology2018Volume: 290Issue: 2pp. 359-367See More RSNA Education Exhibits Usefulness of Spiral Flow Tube for Saline Chaser Capable of Improving Visualization Ability of Subclavian Artery in Cervical CT AngiographyDigital Posters2019Optimization of One-beat 256 Row Detector Coronary CT Angiography Using Low Contrast Media Protocols in Patients with Free Breathing under Automatic Tube Voltage SelectionDigital Posters2018Coronary CT Angiography with Wide Coverage Detector: How to Optimize Contrast Injection and Scan Protocol Based on Patient Size to Reduce Contrast and Radiation DosesDigital Posters2018 RSNA Case Collection Cardiac MyxomaRSNA Case Collection2020Chiari 1 malformation RSNA Case Collection2020Epiploic AppendagitisRSNA Case Collection2022 Vol. 305, No. 2 Metrics Altmetric Score PDF download

The long-term prognostic value provided by Coronary CT angiography

BackgroundRisk-stratification of patients has a major role in the prevention and treatment of cardiovascular disease. The aim was to find the most informative predictors of cardiovascular events in patients undergoing Coronary CT Angiography. MethodsWe carried out a secondary analysis of a large registry dataset. The included population comprises adults aged 18 or older who underwent Coronary CT Angiography of 64-detector rows or greater. We clustered patients based on their characteristics and compared the risk for poor clinical outcomes between the two clusters. ResultsThere were two clusters of patients having different risks for all-cause death, myocardial infarction, and late revascularization [hazard ratios (95%CI) = 2.28 (2.02, 2.57), 1.63 (1.40, 1.89), and 2.46 (2.1, 2.88), all P < 0.001]. The severity of stenosis in the left main coronary artery adjusted for age and sex was the most significant predictor of the high-risk cluster [adjusted odds ratio (95%CI) = 3.35 (2.98, 3.77), P < 0.001]. The severity of stenosis in the first obtuse marginal branch of the left circumflex, distal left circumflex, distal left anterior descending, posterior descending, the first diagonal branch of the left anterior descending, and proximal right coronary artery were important as well (all adjusted odds ratios ≥ 2.52). Cluster profiling showed a higher performance for CT Angiography features (sensitivity = 97.4%, specificity = 85.7%, C-statistic = 98.7%) than calcium, Framingham, and Duke scores in identifying high-risk patients (C-statistic = 82.1, 77.0, and 88.2%, respectively). ConclusionCoronary CT Angiography can accurately risk-stratify patients concerning poor clinical outcomes.

Effectiveness of orthopedic metal artifact reduction among patients undergoing computed tomography at a tertiary setting – A cross-sectional study

Background: In computed tomography (CT), metal implants increase the inconsistencies between the measured data and the linear assumption of the radon transform made by the analytic CT reconstruction algorithm. Aims and Objectives: The aims of this study was to evaluate the effectiveness of orthopedic metal artifact reduction (O-MAR) among patients undergoing CT at a tertiary setting. Materials and Methods: A cross-sectional observational study was conducted on 30 subjects attending the department of radiology for CT scan for 1 year from December 2018 to 2019. The CT scan was performed in 64 detector row (PHILIPS INGENUITY CORE 128 slice) scanner. The patient was asked for the presence of metallic objects/history of implants, and the topo gram confirms it. Image noise was considered as the primary outcome variable. The statistical analysis was performed using the coGuide software and P&lt;0.005. Results: All the thirty participants were analyzed finally. Image noise in plain image type was 79.5 SD of Hounsfield units, and in O-MAR image type, it was 44.01 SD of Hounsfield units denoting a higher percentage of SD in plain than O-MAR images. Conclusion: The O-MAR application helped in improving image quality of CT for patients in the aspect of metal artifact reduction and soft-tissue profile. However, it can also improve diagnostic quality in the evaluation of patients with severe metallic artifacts by decreasing the negative impacts of orthopedic metals.

Laryngeal Radioanatomy

The larynx, a specialized segment of the airways, is the essential organ of phonation, breathing and protection of the lower airways when swallowing by a complex anatomic structures organized around a cartilaginous skeleton. We realized a prospective study on three months, ranging from March 01 to May 31 2020, of patients referred to our service for cervical CT scan or MRI exploration in different contextes. We retained the normal exams. For scanographic exploration we used a multi-slice CT scan consisting of 64 rows of detectors. Helical acquisition in native axial slices 0.627 mm thick from the base of the skull to the arch of the aorta was performed in indifferent breathing after asking the patient not to swallow. Iodinated contrast product was injected according to the administration protocol in a single bolus of 90 ml at an average flow rate of 1.5 ml / s and to perform the acquisition with 50 second delay. A dynamic phonation maneuver (saying “eee” continuously and evenly) was used to analyse the true and false vocal cords. On MRI exploration of the larynx, we used a high-field device (1.5Tesla) with a semi-circular specific surface antenna, the phase oriented in an anteroposterior direction, the 3DT1 spin echo sequence without fat signal saturation was performed. In ultrasound, we used literature data. Knowledge of laryngeal radioanatomy contributes to the diagnosis of laryngeal cancers which occupy an important place in all cancers of the upper aerodigestive tract. They can be diagnosed early and the refinement of their endoscopic exploration and imaging allows them to make a precise extension assessment.

Impact of Several Factors on the Diagnostic Interpretability of Coronary Computed Tomographic Angiography Using a 256-Detector Row CT Scanner.

This study aimed at exploring the impact of patient-related, vessel-related, image quality-related and cardiovascular risk factors on coronary computed tomographic angiography (CCTA) interpretability using 256-detector row computed tomography (CT). One hundred ten patients who underwent CCTA and Invasive Coronary Angiography (ICA) were consecutively, retrospectively enrolled from January 2018 to October 2018. Using ICA as the reference standard, ≥50% diameter stenosis was defined as the cut-off criterion to detect the diagnostic performance of CCTA. Diagnostic reproducibility was investigated by calculating the interrater reproducibility of CCTA. Multiple logistic regression models were performed to evaluate the impact of 14 objective factors. A total of 1019 segments were evaluated. The per-segment sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of CCTA were 76.8%, 93.7%, 91.2%, 67.8%, and 95.9%, respectively. The per-segment diagnostic reproducibility was 0.44 for CCTA. Regarding accuracy, a negative association was found for stenosis severity, calcium load, and hyperlipidaemia. Regarding sensitivity, calcium load and diabetes mellitus (DM) were positively related. Regarding specificity, a negative correlation was observed between stenosis severity and calcium load. Regarding interrater reproducibility, stenosis severity and calcium load were negatively associated, whereas male sex and the signal-to-noise ratio (SNR) were positively related (all p<0.05). Per-segment 256-detector row CCTA performance was optimal in stenosis-free or occluded segments. Heavier calcium load was associated with poorer CCTA interpretability. On the one hand, our findings confirmed the rule-out value of CCTA; on the other hand, improvements in calcium subtractions and deep learning-based tools are suggested to improve CCTA diagnostic interpretability.

Two concepts for ultra-high-resolution polarization-sensitive optical coherence tomography with a single camera.

Two designs with a multiplexed superluminescent diode for ultra-high-resolution spectral-domain polarization-sensitive optical coherence tomography (UHR-PS-OCT) are introduced. In the first design, a Wollaston prism separates orthogonal polarization states next to each other on one linescan camera; the other design uses a beam displacer to separate orthogonal states onto two lines of a linescan camera with multiple rows of detectors. The coherence lengths measured with the two systems were 3.6 µm and 2.9 µm (n=1.38), respectively. Measurements were collected from the fovea of a healthy subject, a healthy subject with astigmatism, and a patient with central serous retinopathy (CSR). A single volumetric scan provides double pass retardance induced by the retinal nerve fiber layer birefringence (RNFL) and its birefringence, the cumulative double pass retardance induced by the Henle fiber layer, and the retardance that is induced by the retinal pigment epithelium-Bruch's membrane complex. The high axial resolution in UHR-PS-OCT is particularly helpful for the measurements of thin retinal tissue, such as the RNFL in the fovea, where birefringence values of around 1°/µm were found. Tilting of the retina due to a CSR or by off centering the imaging beam in the pupil causes an artificial increase in the double pass retardance induced by the RNFL and Henle fiber layer.

Dose length product and outcome of CT fluoroscopy-guided interventions using a new 320-detector row CT scanner with deep-learning reconstruction and new bow-tie filter.

To investigate the dose length product (DLP) and outcomes of CT fluoroscopy (CTF)-guided interventions using a novel 320-detector row CT scanner with deep-learning reconstruction (DLR) and a new bow-tie filter (i.e., Aquilion ONE Prism Edition) and compare with a 320-detector row CT system without DLR and the new bow-tie filter (i.e., Aquilion ONE Vision Edition) (Vision). CTF-guided interventions performed using Prism and Vision were retrospectively investigated in terms of the technical success rates, clinical success rates of biopsies, complications, DLPs of total CT scans (total DLPs) from February 2019 to January 2021. The total CT scans included pre-interventional CT scans, CTF scans during the CTF-guided procedure, additional CT scans for additional treatment, CTF scans for additional treatment, and post-interventional CT scans. In this study, 87 and 85 CTF-guided interventions were performed using Vision (Vision group) and Prism (Prism group), respectively. There was no significant difference in the technical success rate (96.6% vs 98.8%, p = 0.621), clinical success rate of biopsies (92.9% vs 93.4%, p = 1.000), and minor (8.0% vs 7.1%, p = 0.807) and major (0% vs 3.5%, p = 0.119) complications between the Prism and Vision groups. The total DLPs for the Prism group were significantly lower than those for the Vision group regardless of the procedure (278 vs 548 mGy*cm, p < 0.001, in the biopsy and 246 vs 667 mGy*cm, p < 0.001, in the drainage and aspiration). CTF-guided interventions on Prism reduce the total DLP without performance degradation of the intervention. The total DLPs of biopsies and drainages/aspirations in the Prism group decreased by 49 and 63%, respectively.

The diagnostic performance of ultra-low-dose 320-row detector CT with different reconstruction algorithms on limb joint fractures in the emergency department.

The aim of the study was to evaluate whether ultra-low-dose computed tomography (ULD-CT) could replace conventional-dose CT (CD-CT) for diagnosis of acute wrist, ankle, knee, and shoulder fractures in emergency departments (ED). We developed CD-CT and ULD-CT scanning schemes for the various joints of the four limbs and scanned emergency patients prospectively. When performing CD-CT, a conventional bone reconstruction algorithm was used, while ULD-CT used both soft tissue and bone algorithms. A five-point scale was used to evaluate whether ULD-CT image quality affected surgical planning. The image quality and diagnostic performance of different types of scanned and reconstructed images for diagnosing fractures were evaluated and compared. Effective radiation dose of each group was calculated. Our study included 56 normal cases and 185 fracture cases. The combination of bone and soft tissue algorithms on ULD-CT can improve diagnostic performance, such that on ULD-CT, the sensitivity improved from 96.7% to 98.9%, specificity from 98.2% to 100%, positive predictive value from 99.4% to 100%, negative predictive value from 90.2% to 96.6% and diagnostic accuracy ranged from 97.5% to 99.1%. There were no statistically significant differences between ULD-CT and CD-CT on diagnostic performance (p values, 0.40-1.00). The radiation doses for ULD-CT protocols were only 3.0-7.7% of those for CD-CT protocols (all p < 0.01). In the emergency department, the 320-row detector ULD-CT could replace CD-CT in the diagnosis of limb joint fractures. The combination of bone algorithm with soft tissue algorithm reconstruction can further improve the image quality and diagnostic performance.

A novel anteroposterior axis of the tibia for total knee arthroplasty: An upright weight-bearing computed tomography analysis

BackgroundThe traditional anteroposterior (AP) axis (i.e., Akagi’s line) has been widely used as the tibial component AP axis during total knee arthroplasty (TKA). However, this AP axis has been defined based on computed tomography (CT) in a non-weight-bearing supine position. In this study, AP axes of the tibial plateau from upright CT in weight-bearing and non-weight-bearing positions were determined and compared. MethodsThis study included 43 knees from 23 healthy volunteers. CT images were obtained in weight-bearing and non-weight-bearing standing positions using a 320-detector row upright CT scanner. The line perpendicular to surgical transepicondylar axis projected onto the tibia plateau was determined as the AP axis in upright weight-bearing and non-weight-bearing conditions. Angular differences between these two conditions were measured. ResultsThe upright weight-bearing AP axis was positioned in a mean of 7.4 ± 4.3° of internal rotation relative to the traditional AP axis. Distance between the traditional and upright weight-bearing AP axis was 2.9 ± 1.6 mm at the edge of the tibial plateau. The upright non-weight-bearing AP axis was positioned in a mean of 3.5 ± 4.1° of internal rotation relative to the traditional AP axis. Mean angular difference between weight-bearing and non-weight-bearing conditions was 3.9 ± 4.1°. ConclusionsThe upright weight-bearing AP axis was positioned in 7.4° of internal rotation relative to the traditional AP axis, showing one-seventh of the tibial tuberosity away from the medial border of the tibial tubercle, which represents a practical landmark for the tibial component AP axis during TKA.

The left-sided aortic arch variants: prevalence meta-analysis of imaging studies.

To estimate the prevalence of the left-sided aortic arch (LSAA) variants, and the effect of possible moderators on variants' detection. A systematic online literature search was conducted. The pooled prevalence with 95% confidence intervals was estimated for the typical and atypical branching patterns to compare the overall proportions of different variants. Meta-regression analyses were performed to investigate the effect of the subjects' gender and geographical region, and the multidetector computed tomography (MDCT) scanner's technology on the estimated prevalence. In total, 18,075 cases from 23 imaging studies were included and 33 different LSAA variants were detected. The estimated heterogeneity was statistically significant. Based on the estimated prevalence, approximately 77% of the population is expected to have the typical branching anatomy with sequence brachiocephalic trunk-left common carotid artery-left subclavian artery, and 23% variant branching patterns. Approximately 71%, 23%, 2%, and 0.1% of the atypical populations are expected to have two, four, three, and five emerging branches, respectively. The meta-regression analyses showed that the number of detector rows of the MDCT scanner, and the subjects' geographical region are statistically significant moderators of the estimated prevalence. The current findings indicate that the prevalence of the LSAA variant branching anatomy is significantly affected by the subjects' geographical region and the MDCT scanner's technological improvement, with the advanced scanners to facilitate the detection of the aortic arch variants. However, due to the heterogeneity among studies, further research is required.

A Narrative Review on Current Diagnostic Imaging Tools for Dentomaxillofacial Abnormalities in Children.

The current review narrates the findings and discusses the available diagnostic tools for detecting structural abnormalities. The review discusses several diagnostic tools, such as magnetic resonance imaging, cone beam computed tomography, multi detector row CT and positron emission tomography. The vital findings and comparative analysis of different diagnostic tools are presented in this review. The present review also discusses the advent of newer technologies, such as the HyperionX9 scanner with less field of view and 18F-FDG PET/CT (positron emission tomography with 2-deoxy-2-[fluorine-18] fluoro-D-glucose, integrated with computed tomography), which can give more efficient imaging of dentomaxillofacial structures. The discussion of effective comparative points enables this review to reveal the available diagnostic tools that can be used in the detection of dentomaxillofacial abnormalities in the pediatric population. The advantages and disadvantages of each tool are discussed, and the findings of past publications are also presented. Overall, this review discusses the technical details and provides a comparative analysis of updated diagnostic techniques for dentomaxillofacial diagnosis.

Rolling shutter-induced aberrations in laser guide star wavefront sensing

Laser guide star (LGS) Shack–Hartmann (SH) wavefront sensors for next-generation Extremely Large Telescopes (ELTs) require low-noise, large format (∼1 Mpx), fast detectors to match the need for a large number of subapertures and a good sampling of the very elongated spots. One path envisaged to fulfill this need has been the adoption of complementary metal metal-oxide semiconductor detectors with a rolling shutter read-out scheme that allows low read-out noise and fast readout time at the cost of image distortion due to the detector rows exposed in different moments. Here, we analyze the impact of the rolling shutter read-out scheme when used for LGS SH wavefront sensing; in particular, we focus on the impact on the adaptive optics (AO) correction of the distortion-induced aberrations created by the rolling exposure in the case of fast varying aberrations, like the ones coming from the LGS tilt jitter due to the up-link propagation of laser beams. We show that the LGS jitter-induced aberration for an ELT can be as large as 100-nm root-mean-square, a significant term in the wavefront error budget of a typical AO system on an ELT, and we discuss possible mitigation strategies.

Radiation dose reduction method combining the ECG-Edit function and high helical pitch in retrospectively-gated CT angiography

IntroductionThe purpose of this study was to demonstrate that dose reduction does not compromise image quality when combining high helical pitch (HP) and the ECG-Edit function during low HP retrospectively gated computed tomography angiography (CTA). MethodsThis study made use of a pulsating cardiac phantom (ALPHA 1 VTPC). The heart rate (HR) of the cardiac phantom was changed in five intervals, every 5 beats per minute (bpm), from 40 to 60 bpm. Evaluation of a range of HR was important because data loss might occur when combining a low HR and high HP. We performed retrospectively gated CTA scans five times using a low HP (0.16) and high HP (0.24), for each of the five HR intervals, using a 64-detector row CT scanner. The CT volume dose index (CTDIvol) was recorded from the CT console of each scan. For the images with data loss, data were repaired using the ECG-Edit function. We compared the CTDIvol, estimated cardiac phantom volume, and the visualization of the coronary ladder phantom between HP 0.16, with or without repaired HP 0.24, using the ECG-Edit function. ResultsData loss occurred with a HR of 40 bpm and 45 bpm when using HP 0.24. The CTDIvol was reduced by approximately 33% with HP 0.24 when compared with HP 0.16. There were no significant differences in the mean cardiac motion phantom volume and visualization scores between HP 0.16 and with and without repaired HP 0.24 using the ECG-Edit function (p < 0.05). ConclusionThe ECG-Edit function is potential useful for repairing the lost data in patients with a low HR, and when combined with a high HP, it is possible to reduce the radiation dose by approximately 33%. Implications for practiceThe ECG-Edit function and high HP may be a viable option in pediatric CTA studies.

Performance of Hybrid Imaging in the Diagnosis of Coronary Artery Disease

Single-photon emission computed tomography (SPECT) and computed tomography coronary angiography (CTCA) are usually performed independently in patients with suspected coronary artery disease. We assessed the hypothesis that hybrid SPECT/CTCA imaging results in higher diagnostic accuracy than either method alone, particularly in cases presenting with high levels of coronary calcification. A total of 243 major coronary vessels in 81 patients with known or suspected coronary artery disease were screened using SPECT with semiconductor detectors and CTCA with 256-detector row computed tomography. Patients who were diagnosed with myocardial ischemia underwent coronary angiography. Coronary angiography results were defined as positive for stenosis when the stenosis diameter was >70% or fractional flow reserve was <0.8. These data were then compared with a fused image of the SPECT and CTCA datasets generated using a dedicated workstation. To detect significant coronary artery stenosis, the respective sensitivity, specificity, and accuracy were 73%, 61%, and 67% with SPECT alone, 96%, 44%, and 67% with CTCA alone, and 95%, 75%, and 84% with hybrid imaging. Moreover, hybrid imaging allowed the accurate diagnosis of 47 vessels with severe calcification that CTCA alone could not evaluate correctly. Hybrid imaging shows greater diagnostic accuracy than single-modality evaluation through more comprehensive information on potential coronary stenosis and its hemodynamic significance.

Increase in tibial internal rotation due to weight-bearing is a key feature to diagnose early-stage knee osteoarthritis: a study with upright computed tomography

BackgroundThe classification of knee osteoarthritis is an essential clinical issue, particularly in terms of diagnosing early knee osteoarthritis. However, the evaluation of three-dimensional limb alignment on two-dimensional radiographs is limited. This study evaluated the three-dimensional changes induced by weight-bearing in the alignments of lower limbs at various stages of knee osteoarthritis.MethodsForty five knees of 25 patients (69.9 ± 8.9 years) with knee OA were examined in the study. CT images of the entire leg were obtained in the supine and standing positions using conventional CT and 320-row detector upright CT, respectively. Next, the differences in the three-dimensional alignment of the entire leg in the supine and standing positions were obtained using 3D-3D surface registration technique, and those were compared for each Kellgren–Lawrence grade.ResultsGreater flexion, adduction, and tibial internal rotation were observed in the standing position, as opposed to the supine position. Kellgren–Lawrence grades 1 and 4 showed significant differences in flexion, adduction, and tibial internal rotation between two postures. Grades 2 and 4 showed significant differences in adduction, while grades 1 and 2, and 1 and 3 showed significant differences in tibial internal rotation between standing and supine positions.ConclusionsWeight-bearing makes greater the three-dimensional deformities in knees with osteoarthritis. Particularly, greater tibial internal rotation was observed in patients with grades 2 and 3 compared to those with grade 1. The greater tibial internal rotation due to weight-bearing is a key pathologic feature to detect early osteoarthritic change in knees undergoing osteoarthritis.